/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-2009 The eXist Project
* http://exist-db.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $Id$
*/
package org.exist.xquery.functions.fn;
import org.apache.log4j.Logger;
import java.text.Collator;
import java.util.Comparator;
import java.util.TreeSet;
import org.exist.dom.QName;
import org.exist.xquery.Cardinality;
import org.exist.xquery.Constants;
import org.exist.xquery.Dependency;
import org.exist.xquery.Function;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.Profiler;
import org.exist.xquery.ValueComparison;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.AtomicValue;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.NumericValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceIterator;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;
import org.exist.xquery.value.ValueSequence;
/**
* Implements the fn:distinct-values standard library function.
*
* @author wolf
* @author perig
*/
public class FunDistinctValues extends CollatingFunction {
protected static final Logger logger = Logger.getLogger(FunDistinctValues.class);
public final static FunctionSignature signatures[] = {
new FunctionSignature(
new QName("distinct-values", Function.BUILTIN_FUNCTION_NS, FnModule.PREFIX),
"Returns a sequence where duplicate values of $atomic-values, " +
"based on value equality, have been deleted.",
new SequenceType[] {
new FunctionParameterSequenceType("atomic-values", Type.ATOMIC,
Cardinality.ZERO_OR_MORE, "The atomic values")
},
new FunctionReturnSequenceType(Type.ATOMIC, Cardinality.ZERO_OR_MORE,
"the distinct values sequence")
),
new FunctionSignature(
new QName("distinct-values", Function.BUILTIN_FUNCTION_NS, FnModule.PREFIX),
"Returns a sequence where duplicate values of $atomic-values, " +
"based on value equality specified by collation $collation-uri, " +
"have been deleted.",
new SequenceType[] {
new FunctionParameterSequenceType("atomic-values", Type.ATOMIC,
Cardinality.ZERO_OR_MORE, "The atomic values"),
new FunctionParameterSequenceType("collation-uri", Type.STRING,
Cardinality.EXACTLY_ONE, "The collation URI")
},
new FunctionReturnSequenceType(Type.ATOMIC, Cardinality.ZERO_OR_MORE,
"the distinct values sequence")
)
};
public FunDistinctValues(XQueryContext context, FunctionSignature signature) {
super(context, signature);
}
/* (non-Javadoc)
* @see org.exist.xquery.PathExpr#returnsType()
*/
public int returnsType() {
return Type.ATOMIC;
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#eval(org.exist.xquery.StaticContext, org.exist.dom.DocumentSet, org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
*/
public Sequence eval(Sequence contextSequence, Item contextItem)
throws XPathException {
if (context.getProfiler().isEnabled()) {
context.getProfiler().start(this);
context.getProfiler().message(this, Profiler.DEPENDENCIES,
"DEPENDENCIES", Dependency.getDependenciesName(this.getDependencies()));
if (contextSequence != null)
{context.getProfiler().message(this, Profiler.START_SEQUENCES,
"CONTEXT SEQUENCE", contextSequence);}
if (contextItem != null)
{context.getProfiler().message(this, Profiler.START_SEQUENCES,
"CONTEXT ITEM", contextItem.toSequence());}
}
final Sequence seq = getArgument(0).eval(contextSequence, contextItem);
final Collator collator = getCollator(contextSequence, contextItem, 2);
final TreeSet<AtomicValue> set = new TreeSet<AtomicValue>(new ValueComparator(collator));
final ValueSequence result = new ValueSequence();
Item item;
AtomicValue value;
boolean hasAlreadyNaN = false;
for (final SequenceIterator i = seq.iterate(); i.hasNext();) {
item = i.nextItem();
value = item.atomize();
if (!set.contains(value)) {
if (Type.subTypeOf(value.getType(), Type.NUMBER)) {
if (((NumericValue)value).isNaN()) {
//although NaN does not equal itself, if $arg
//contains multiple NaN values a single NaN is returned.
if (!hasAlreadyNaN) {
set.add(value);
result.add(value);
hasAlreadyNaN = true;
}
} else {
set.add(value);
result.add(value);
}
} else {
set.add(value);
result.add(value);
}
}
}
if (context.getProfiler().isEnabled())
{context.getProfiler().end(this, "", result);}
return result;
}
public final static class ValueComparator implements Comparator<AtomicValue> {
Collator collator;
public ValueComparator(Collator collator) {
this.collator = collator;
}
/* (non-Javadoc)
* @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
*/
public int compare(AtomicValue o1, AtomicValue o2) {
try {
if (ValueComparison.compareAtomic(collator, o1, o2,
Constants.TRUNC_NONE, Constants.EQ))
{return Constants.EQUAL;}
else if (ValueComparison.compareAtomic(collator, o1, o2,
Constants.TRUNC_NONE, Constants.LT))
{return Constants.INFERIOR;}
else if (ValueComparison.compareAtomic(collator, o1, o2,
Constants.TRUNC_NONE, Constants.GT))
{return Constants.SUPERIOR;}
//Fallback
else
{return o1.compareTo(collator, o2);}
} catch (final XPathException e) {
//Values that cannot be compared, i.e. the eq operator
//is not defined for their types, are considered to be distinct
return Constants.INFERIOR;
}
}
}
}